count() is very slow

i have about one Billion series, and i need get specific rows size

query sql --> select count(*) from softTest where id = 'softId'

it's has execute one hour ,but has not result

it's me use error? influxdb oss version is 1.8.6

Start by reproducing the reported `select count(*) from softTest where id = 'softId'` query against InfluxDB OSS 1.8.6 with a comparable series count. Investigate whether the hour-long execution is expected for this query and identify the relevant performance limitation or behavior. Done means explaining the cause and documenting or addressing a verified fix.

Written by the indexing model from the issue text.